subject:- separation process

chapter: Membrane

As a normal routine, a kidney failure patient undergoes a session of haemodialysis treatment every other day at a dialysis centre. On one fine day, prior to the treatment, his Blood Urea Nitrogen (BUN) concentration was measured to be 140 mg/dL. The dialysis treatment took 4 hours to complete. The specification of the dialysis membrane used is as follow: Membrane area - 1.5 m2 Inner fibre diameter = 200 m Membrane thickness - 15 um Average pore size = 10 nm BUN reflects only the nitrogen content of urea, whereas urea measurement reflects the whole of the molecule. Urea is approximately 2.14 that of BUN. Fresh dialyzing fluid is mused for the treatment. Since the volume of the dialyzing fluid is relatively large, it can be assumed that the concentration of the dialyzing fluid is unchanged. Given: kes = 1.25 x 105 m/s; kez = 3.33 x 10 m/s; distribution coefficient, K' = 1.5; diffusivity, Da - 7.0 x 10-11 m/s; Molecular weight (MW) of Nitrogen gas = 28; MW of aurea is 60. (a) Calculate the flux and the rate of removal of urea at steady state in g/h. [30 Marks) [CO2, PO2, C5) (b) Calculate the final concentration of urea in his blood after the 4 hour treatment